Correlation of Tensile Properties of Pressure Vessel Steels by Shear Punch and Small Punch Test Methods
About: The article was published on 2012-11-09. It has received 3 citations till now. The article focuses on the topics: Pressure vessel.
TL;DR: In this paper, the performance of the Small Punch Test (SPT) on 316-L steels was analyzed by a FEM model, validated by an additively manufactured 316-l SLM (Selective Laser Melting) stainless steel, in terms of thickness evolution, local deformation and instantaneous strain rate during SPT testing.
Abstract: The Small Punch Test, SPT, has been widely used by scientists for the mechanical characterization of nuclear materials and different applications. This technique is able to provide an approximation of mechanical properties from a very small amount of material. However, the inhomogeneous distributions of local stresses and strains, coupled to the response of the material hinder accurate predictions of the mechanical properties in terms of tensile tests parameters. Additionally, the determination of the instantaneous strain rate, as the test proceeds, remained a pending issue. This article analyses the predictions of SPT on 316 L steels by a FEM model, validated by an additively manufactured 316 L SLM (Selective Laser Melting) stainless steel, in terms of thickness evolution, local deformation and instantaneous strain rate during SPT testing. This alternative analysis shows that the deformation behaviour and, thus, the final form of the sample is affected by the strain hardening behaviour, which it has an influence on the instantaneous local strain rate. The instantaneous local strain rate was calculated for two dissimilar 316 L austenitic stainless steel, one “hardened”, characterized by low ductility but very high yield strength (YS) and ultimate tensile strength UTS, and another “annealed”, characterized by very low YS and large ductility, typical of annealed 316 L steel. The calculated central and minimum thicknesses, strain and instantaneous local strain rate, are not linear as SPT testing proceeds. Therefore, they are fitted to polynomial equations for both annealed and hardened 316 L steels. These functions allow, for instance, LVDT measurement corrections for appropriate SPT curve analysis, and proper true strain rate measurements for creep (SPCT) data analysis.
TL;DR: Small specimen mechanical testing is an exciting and rapidly developing field in which fundamental deformation behaviours can be observed from experiments performed on comparatively small amounts of data as discussed by the authors, which can be found in this paper.
Abstract: Small specimen mechanical testing is an exciting and rapidly developing field in which fundamental deformation behaviours can be observed from experiments performed on comparatively small amounts o...
••19 Nov 2015
TL;DR: In this article, the authors present the results of cyclic ball indentation test method as well as cyclic small punch test method that is used to generate the fatigue data at different stress levels.
Abstract: Fatigue properties of materials is an important input while estimating the residual life of critical components. Fatigue data (stress vs. cycles or strain vs. cycles or fatigue crack growth rate data) are used to predict the residual life. One of the shortcomings of this method is that it relies on data generated from virgin material or surveilance coupons which have been exposed to the harsh environment over a period of time. Often the quantity of material available for fatigue data is small and being probabilistic in nature, fatigue data requires multiple specimens to be tested at any given stress/strain levels. This has prompted us to develop test procedures to determine the fatigue data of materials from small volume of material. In this paper, we present the results of cyclic ball indentation test method as well as cyclic small punch test method that is used to generate the fatigue data at different stress levels. There are several fine details relating to these test technique — viz., establishing a equivalent damage criteria for failure life with standard LCF/HCF test specimens. Apart from this, several variables that influence the testing process needs to be considered.This paper briefly reviews the viability of using miniature specimen test techniques, particularly cyclic ball indentation and cyclic small punch testing for extracting the fatigue data, based on the author’s previous work. It is shown that, both the test techniques are capable of detecting and quantifying the prior fatigue damage in the materials.Copyright © 2015 by ASME